1. Field of the Invention
This invention relates to blends of poly(phenylene ether) resins and thermoplastic naphthalate-type polyesters that exhibit enhanced properties, such as increased elastic modulii.
2. Brief Description of the Related Art
Poly(phenylene ether) resins (referred to hereafter as "PPE") are commercially attractive materials because of their unique combination of properties, including, for example, high temperature resistance, dimensional and hydrolytic stability, and electrical properties. Furthermore, the combination of PPE with polyesters into compatibilized PPE-polyester blends has been sought after for additional overall properties such as, for example, chemical resistance, high strength, and high flow. Examples of such compatibilized blends can be found in U.S. Pat. Nos. 4,845,160, 5,089,566, 5,153,267, 5,247,006, 5,010,144 and 5,089,567, which are incorporated herein by reference. The properties of these blends can be further enhanced by the addition of various additives such as impact modifiers, heat stabilizers, antioxidants and fillers. The physical properties of compatibilized blends comprising PPE and polyesters make them attractive for a variety of end-use articles in the automotive market, especially for lighting and under hood components.
All of the aforementioned examples of compatibilized PPE-polyester blends have utilized terephthalate diacid type polyesters such as poly(1,4-butylene terephthalate) and poly(1,2-ethylene terephthalate) or various derivatives thereof for the polyester component. A disadvantage of these terephthalate diacid type polyesters is their relatively low Tg's (PBT Tg is about 45.degree.-50.degree. C. and PET Tg is about 70.degree.-75.degree. C.). The relatively low Tg's of the terephthalate-type polyesters result in PPE-polyester blends with somewhat limited high heat capabilities for certain demanding high temperature applications. Included in these demanding applications are the aforementioned lighting and under hood components.
It is therefore apparent that a need continues to exist for alternative strategies for PPE-polyester blends which overcome some of the aforementioned difficulties.